net: net->nsid_lock does not need BH safety

At the time of commit bc51dddf ("netns: avoid disabling irq
for netns id") peernet2id() was not yet using RCU.

Commit 2dce224f ("netns: protect netns
ID lookups with RCU") changed peernet2id() to no longer
acquire net->nsid_lock (potentially from BH context).

We do not need to block soft interrupts when acquiring
net->nsid_lock anymore.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Guillaume Nault <gnault@redhat.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250627163242.230866-1-edumazet@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>